May 23

Sarah Robertson

Comet Goldfish – Meet The Oldest and Most Beautiful Goldfish

Fishkeeping is a rewarding hobby that can be enjoyed by people of all ages. There are many different types of fish that can be kept, and each has its own unique requirements. One type of fish that is popular among beginning hobbyists is the comet goldfish.

The Comet goldfish is one of the oldest varieties of goldfish. They are well-known freshwater fish that have been around for many years in the aquarium industry. They're adored by a lot of people for their attractiveness and unusual behaviors.

Goldfish with a longer, flowing tail is known as comet goldfish. They were almost certainly one of the first goldfish types developed. Comets are a "fancy" kind of goldfish that is believed to a hardy fish than some of the more inbred types. In this care guide, we will cover everything you need to know about keeping comet goldfish healthy and happy in your home aquarium.

Comet Goldfish Appearance

While they appear to be identical to typical Goldfish, you'll notice several significant physical distinctions if you look closely. The most apparent distinction is the tail.

Goldfish have short, rigid tails whereas Comet Goldfish have flowing forked tails. Their tailfins glide gracefully through the water, even when they're swimming at top speed. In fact, the shape of a fish's tailfin is what gave it its name!

A single-tailed Goldfish is a Comet. This indicates that they have a single forked tail with two tips rather than a twin tail with four. They come in a variety of colors. The most popular variants are yellow, orange, white, and bright red. You could also encounter a brown specimen from time to time.

Large dorsal, a thin anal fin, and two lengthy pectoral fins adorn this beautiful comet fish. All of the fins are semi-translucent and can be colored however you want them to be.

You can also see a variety of "spotted" Comet Goldfish. They're mostly white and have brilliant red spots all over their body. These fish are often known as Sarasa Comet Goldfish.

Differentiating Gender 

There are many ways to differentiate the genders of Comet goldfish. The following are some of the most reliable methods:

Young Fish

It's impossible to determine the gender of a goldfish that is less than a year old. However, because goldfish reproduce in groups, this does not imply that someone seeking to breed must wait for the fish to mature. Purchasing a collection of six comets is your greatest chance of getting good results.

Comet Goldfish Variants

Pectoral Fins 

The pectoral or side fins are one of the most effective methods to determine a comet goldfish's sex in older specimens. The first fin ray of males' pectorals is typically thicker than those on females.

This does, however, take into account that the goldfish are of comparable age and have received the same level of care. A larger female goldfish may have thicker fin rays than a smaller male kept in less-than-ideal circumstances.

Breeding Tubercles

The best method to determine the sex of a comet goldfish is when breeding season begins. The males have prickly bumps on their gill covers and the front of their pectoral fins. These breeding tubercles, on rare occasions, resemble the bumps and formations visible in fish diseases such as ich. They are a positive indication; only if a fish is in ideal ecological circumstances and willing to breed will it develop spawning tubercles.

Body Shape 

The physical appearance of male and female porcelain crabs is similar. When viewed from above, females are typically wider-bodied than males. This works best during the breeding season when females expand with roe. When viewing comets from the side, this technique is less successful; however, when looking down from the top, the distinction between male and female is more apparent.

Comet Goldfish Variants

While the Comet Goldfish is a single-tailed variety, there are several other popular types of comet goldfish that you should be aware of. The following are some of the most common:

Sarasa Comets

The Sarasa comets are red-and-white in color and resemble the Kohaku color pattern in wild carp. The Sarasa Comet is a hardy fish with lengthy flowing fins. The erect dorsal fins are distinctively more slender than those of a typical goldfish, and they have a single tail.

Despite the fact that the Sarasa Comet comes from China, its name originates from Japan. They are capable of growing up to 14 inches in length.

Tancho Single-Tail Comet 

The Tancho single-tail goldfish Comet is a silver variety with a red patch on its head. This beautiful fish can grow up to a length of 4.0 inches. The fins of the Tancho Single-tail Comet are lengthy and transparent.


The goldfish has been around since the early days of fishkeeping. They were selectively bred from the Common Goldfish and have grown in popularity rapidly. Comet goldfish are closely related to Prussian carps as the common goldfish are said to be developed from this particular variety.  These species are readily available in local pet shops, prized at carnivals, and even used as feeder bait at fishing stores because they are so simple to breed.

However, these beautiful fishes cannot be found in the wild. They were originally found in Asia and eventually made their way over to Europe and North America and later to the rest of the world.

Common Goldfish

Comet Goldfish Size

Comet goldfish are some of the largest goldfish varieties, with some specimens reaching up to 16 inches in length. However, the average size of a comet goldfish is usually around 10-12 inches. The size of a fish depends on various factors such as genetics, diet, and water conditions.

Comet Goldfish Lifespan 

The average lifespan of a comet goldfish is around 10-15 years, but some have been known to live for 20 years or more with proper care. This depends largely on the water conditions, diet, and level of care that they receive.

Behavior & Temperament 

The Comet Goldfish is a friendly fish and is a lot of fun to observe in your aquarium. They are cold water fish that are quite docile, but they like to stay active. You'll frequently see them zip across your fish tank at high speed, which is why you need plenty of room.

These species, even though they are very active fish, will not exhibit any signs of aggression toward other fish. In fact, they get along with almost every living thing. Their behavior around tiny fish is the only thing to be concerned about. Small tank companions should generally be avoided since they may easily be confused with food.

The only time you'll see aggression from a Comet Goldfish is during the spawning season. The male will chase the female around and nip at her fins in an attempt to get her to release her eggs. This is perfectly normal behavior, and it shouldn't be cause for concern.

Comet Goldfish Care 

Comet Goldfish are relatively easy to care for and make a great choice for beginning hobbyists. They're hardy fish that can tolerate a wide range of water conditions, making them ideal for those who are just starting out. However, it's important to provide them with the best possible care in order to ensure a long and happy life.

Tank Size 

The minimum tank size for a small school of comet goldfish, say four or five, is 30-40 gallons of water. However, it's best to go with a larger tank if possible. These coldwater fish grow quickly and can reach an average of 12 inches in length, so they need plenty of space to swim. It's also important to have a large tank because they produce a lot of fish waste. A larger tank will help to keep the water quality high and will make it easier to care for your fish.

Water Requirements

Comet Goldfish are not picky when it comes to water conditions. They can tolerate a wide range of pH levels and temperatures. However, it's important to maintain stable water conditions in order to keep your fish healthy. The ideal temperature range for comet goldfish is 65-75 degrees Fahrenheit. The pH level should be between 6.5 and 7.5. Water hardness should be between 5 and 20 dH.

Filtration and Aeration

Comet Goldfish produce a lot of waste, so it's important to have a good filtration system in place. A canister filter or a hang-on-back filter will work well for a comet goldfish tank.

Be sure to choose a filter that is rated for at least double the size of your tank. For example, a 40-gallon tank should have a filter that is rated for at least 80 gallons. Also, be sure to change the filter media regularly and clean the filter itself according to the manufacturer's instructions. A dirty filter can lead to poor water quality and can make your fish sick.

It's also important to have plenty of aeration in the tank. These Goldfish species are heavy breathers and need a lot of oxygen in the water. An air stone or an aquarium bubbler will help to provide the aeration that your fish need. A water conditioner is also recommended. 

Comet Goldfish Care

Tank Decorations

Comet Goldfish are not picky when it comes to tank decorations. They can be kept in a bare-bottom tank or a tank with live plants. However, it's important to make sure that any decorations you choose are safe for goldfish. Sharp edges can damage their fins and cause injury. Also, be sure to avoid using any chemicals in the tank, as they can be harmful to your fish.

Live plants are a great addition to any goldfish tank. Not only do they provide your fish with hiding places and help to oxygenate the water, but they also help to keep the water clean. Some good plant choices for goldfish tanks include Java moss, Hornort, and Anacharis. Other decoration options include driftwood, rocks, and caves.

Goldfish are notorious for upending plants, so it's important to choose plants that are heavy enough to stay in place. Also, be sure to avoid using any poisonous plants in the tank. 


Comet Goldfish are voracious eaters and will accept a wide variety of food. They are omnivorous, so they need both plant and animal matter in their diet. Make sure to provide them with a healthy diet that includes vitamins, minerals, proteins, and carbohydrates.

A good quality goldfish pellets or flakes can provide your fish with the nutrients they need. You can also supplement their diet with frozen foods or live foods, such as brine shrimp or bloodworms. Goldfish will also eat vegetables, such as zucchini, lettuce, and spinach. Be sure to chop the vegetables into small pieces so that your fish can easily consume them.

Foods to Avoid

There are several foods that are to be avoided as they can be harmful or even deadly to goldfish. These include foods rich in fat, such as cheeses and meats. Never feed them bread, as it will expand in their stomach and can cause serious health problems. Also, avoid feeding them avocados, as the pits can be poisonous to goldfish.

When to Feed?

Comet Goldfish should be fed once or twice a day. They should only be given as much food as they can eat in 2-3 minutes. Overfeeding can lead to health problems, such as obesity and swim bladder disease.

Make sure to remove any uneaten food from the tank so that it doesn't decompose and pollute the water.


This species of fish are susceptible to a wide range of diseases. The following are some of the most common diseases that affect goldfish:

Foods to Avoid
  • Parasites-The most hazardous time in a fish's life for coming into contact with a parasite is when it is first purchased from the pet store. In pet shops, various sources and concentrations of fish are combined in different methods, allowing parasites to move via water and on equipment. Parasitic infections in goldfish include missing scales, flashing, bruising, lethargy, or sudden death. White spot disease, Trichodina, Flukes, Costia, Anchor worms, fish lice, and Chilodonella are the most common parasitic illnesses in goldfish.
  • Popeye-This common disease is usually the result of an injury or infection and can be caused by a number of different bacteria or fungi. It is characterized by one or both eyes protruding from the socket and may also be accompanied by cloudy eyes, bulging eyes, or blindness. There is no proper cure for Popeyes.
  • Swim Bladder-The swim bladder is an internal gas-filled sac that helps the fish to maintain its buoyancy. If the swim bladder becomes damaged, the fish may have trouble swimming and may even sink to the bottom of the tank. Swim bladder disease is usually caused by constipation, obesity, or bacterial infection.
  • Neurofibromas-Neurofibromas are lumps or bumps that can appear in any fish. According to some experts, they are normal in comet goldfish, especially those kept outside. Neurofibromas develop deep within the skin's layers and are extremely difficult to cure. They may often grow a "stalk" and fall off before regenerating. Because these benign tumors originate from neural tissue, there is presently no therapy that can target them particularly.
  • Polycystic Kidney Disease-Goldfish are susceptible to a disease that causes cysts in their kidneys, which can result in kidney malfunction and serious tissue damage. Unfortunately, the cause of this illness is unknown, and there is no cure. The kidneys will not recover after they have been damaged in many other species. Clinical symptoms of polycystic kidney disease include a fish swallowing a lot of air at the surface, lethargy, and a protruding abdomen.
  • Buoyancy Disorders- This beautiful fish can suffer from both bad and good buoyancy problems. After eating, positive buoyancy conditions are most common. Goldfish that feed vigorously at the surface may inadvertently inhale too much air. It will most likely be expelled into the GI tract or the swim bladder. The fish returns to normal when the extra air is eliminated. Permanent positive buoyancy disorders can occur as a result of an oval malfunction. To correct these problems, surgery is often required.


Comet Goldfish are hardy fish that can live for a long time with proper care. By following the tips mentioned below, you can help ensure that your goldfish stays healthy and enjoys a long and happy life.

  • Buy your goldfish from a reputable source.
  • Quarantine new arrivals for at least two weeks.
  • Frequent water change is suggested.
  • Keep the tank clean.
  • Feed your goldfish a variety of healthy foods.
  • Make sure not to overfeed them.
  • Observe your fish closely for any signs of illness.


The following are some of the most common symptoms that may indicate that your goldfish is sick:

  • Loss of appetite
  • Frequent yawning or gasping at the surface
  • Bulging eyes
  • Listlessness or lethargy
  • Clamped fins
  • Hanging at the water surface
  • White spots on the body or fins
  • Red streaks or blotches on the body or fins


Because Comet Goldfish breeding necessitates a large environment, it is not commonly done by novice hobbyists. If you are interested in breeding Comet Goldfish, it is best to consult with a professional. However, if you are determined to breed Comet Goldfish on your own, here is some information that may be of assistance.

Select the Breeding Pair 

This is the first step in breeding Comet Goldfish. You will need to choose some males and females that are healthy and of good quality. There are some things you should look for when choosing your breeding stock:

  • The fish should be at least two years old.
  • They must have a well-proportioned physique.
  • The desire to eat should be strong.
  • Males and females should be of similar size.
  • There should not be any ailments or abnormalities in the fish.

Set up the Breeding Tank

The breeding tank should be at least 50 gallons in size. It should also have a filter and a heater to maintain the water temperature at around 68-72 degrees Fahrenheit. The tank should also be equipped with a spawning mop or some type of vegetation on which the female can lay her eggs.

Condition the Breeding Stock 

Conditioning refers to the process of getting the fish ready for breeding. This is an important step in the breeding process as it will help increase the chances of a successful spawn. To condition your fish, there are a few things you will need to do:

For two to three weeks, feed the fish live foods such as brine shrimp, daphnia, or bloodworms.

Make sure to increase the feeding frequency as the spawning date approaches.

During this time, gradually increase the water temperature in the tank until it reaches 68-72 degrees Fahrenheit.

After the conditioning period is over, do a partial water change and then introduce the female to the tank.


The process of spawning can be time-consuming, and it may take many hours. During this period, pay close attention to the fish. To begin the breeding cycle, you must replicate the warmth of spring. Begin by keeping a cooler temperature for a month or more. Then, gradually raise the temperature levels to about 70 degrees Fahrenheit (21 degrees Celsius).

When the temperature reaches 70°F, fish pair off and breed. Males will pursue females around the environment. In a big pond, it may be quite chaotic. The female will release her eggs, and the male will fertilize them. Once the parents have been removed from the tank, they will not exhibit any parental behaviors and will usually eat any eggs they can find. It will take about 3-7 days for the eggs to hatch.

Fry Care

The newly hatched fry is very small and needs to be kept in a separate tank. The fry tank should be kept at a temperature of 70-75°F to ensure that the eggs survive as well as possible. The quality of the eggs will be reduced, at temperatures below 65°F. It should be adequately aerated and have a sponge filter to keep the water quality high.

There is no need to feed them for the first few days as they will live off their yolk sacs. After a week, you can start feeding them live foods such as baby brine shrimp or daphnia. You can also give them finely ground flake food. As they grow, you can give them larger live foods and pellets. It is important to remember to remove any uneaten food as it will pollute the water.

When the fry reaches about two inches in size, it can be moved to a larger tank. It is important to make sure that the fry is well-acclimated to their new environment to avoid any stress.


How to Identify Comet Goldfish Male or Female

How to Identify Comet Goldfish Male or Female?

The sex of a comet goldfish may be determined during the breeding season by looking at its genital organs. On the females, spiky bumps appear on the gill covers and the front of the pectoral fins. These breeding tubercles can sometimes be mistaken for ich-related growths.

How Long Does It Take for a Comet Goldfish to Reach Full Size? 

During its first month, they may develop up to 50% each week. It will take them around 3-4 years to reach their full size.

Can Comet Goldfish Live in a Fish Bowl? 

No, they cannot. Comet goldfish require a tank that is at least 20 gallons in size. They also need a filter and a heater to maintain the water temperature at around 68-72 degrees Fahrenheit.

How Many Comet Goldfish Should Be Kept Together? 

Ideally, you should keep at least two comet goldfish together. They are social creatures and will do best in groups. If you plan on keeping more than two fish, you will need to increase the size of the tank accordingly.

Do Comet Goldfish Eat Algae? 

Yes, they do. Comet goldfish are known to be good algae eaters. One benefit of keeping them in your aquarium is that they will help to keep the tank clean.

Do Comet Goldfish Need a Filter? 

Yes, they do. Comet goldfish produce a lot of waste, and a filter is necessary to keep the water quality high. When choosing a filter for your comet goldfish, make sure that it is rated for at least twice the size of your tank.

How Often Do Comet Goldfish Need to Be Fed?

Comet goldfish should be fed once or twice a day. They are not fastidious eaters and will accept most types of food. Some comet goldfish hobbyists prefer to fast their fish one day a week to help keep them healthy.

How Fast Do Comet Goldfish Breed?

An individual fish can lay up to 10,000 eggs in six weeks. After spawning is done, the fish should be removed from the tank since they may consume the eggs. The eggs will hatch within a week. They may be added to the tank with large fish once they reach 1 inch in length.


The Comet Goldfish is one of the most popular goldfish in the world.  They are very peaceful fish and can be a great addition to any outdoor ponds or aquarium. It's not difficult to comprehend why. They're a pleasure to care for since to their distinct personalities and delicate appearances. They are an all-around good choice for first-time goldfish owners as well as experienced aquarists.

Comet goldfish are incredibly easy to feed since they're not picky eaters. However, it is very important to provide them with a high-quality diet. They will accept most types of food including live foods, pellets, and flakes. It's important to remove any uneaten food as it can pollute the water.

Weekly water change is recommended to keep the tank clean. They should be fed once or twice a day. Maintaining a tank that is at least 20 gallons is necessary for comet goldfish since they produce a lot of waste. A filter is also essential to keep the water quality high.

If you're looking for a goldfish that is easy to care for and has a beautiful appearance, the comet goldfish is a great choice. They are an all-around excellent addition to any aquarium. However, make sure to buy them from reputable breeders or fish keepers to avoid any health issues.

Sarah Robertson

I am a passionate blogger who also happens to be a fish keeping enthusiast. Writing about my hobby is something that I absolutely love to do, and it's no secret that my chosen topic is always centered around fish keeping.

Sarah Robertson

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